This invention relates in general to methods and apparatus for delivering a liquid into the colon and, more specifically to a method and apparatus for fully delivering a selected quantity of a liquid well into the colon.
Conventionally, when it is desired to implant a selected liquid, solution or mixtures of particulate materials in a liquid carrier, well up into the colon, a plastic tube is connected between a rectal catheter and a bucket-like liquid container, the catheter is inserted as far as necessary into the colon and the bucket is elevated to allow the liquid to flow into the colon using the force of gravity.
This arrangement, while in general use, has a number of problems. The equipment is cumbersome and spillage or inadvertent release of liquid often occurs. A clip on the plastic tube serves as a valve so that liquid flow begins only when the clip is released, after the other components are ready. The clip may leak and is often difficult to manipulate.
With small amounts of liquid, there may not be sufficient hydrostatic head to force all of the liquid through the catheter, especially when the liquid is relatively thick or is a mixture of particles in the liquid. Also, bubbles in the tube will often prevent flow of the liquid. In order to eliminate bubbles, the catheter end must be raised above the liquid level in the container, the clip released, the catheter lowered until a free flow of liquid from the catheter begins, then the clip replaced. Where a reasonably precise amount of liquid is to be administered, the loss of varying amounts of liquid during bubble elimination will make administration of precise amounts very difficult. Furthermore, bubbles may later enter through the catheter tip if the catheter tube is inadvertently squeezed and released while beginning insertion into the colon.
Kinks in the catheter tube will also prevent flow of the liquid by gravity and are often difficult to prevent or eliminate. Often, the catheter must be removed resulting in considerable spillage of the liquid being implanted, with the implantation then repeated. The spillage is both messy and expensive where a costly material is being implanted.
Attempts have been made to use a rubber bulb type syringe connected to the catheter to reduce some of these problems. However, it is not possible to entirely empty the syringe and liquid is likely to remain in the syringe, tube and catheter, resulting in incomplete implantation, an inaccurate and indefinite quantity implanted, and a waste of material not implanted.
Thus, there is a continuing need for improved devices for implanting various liquids in the colon that can implant a precise desired amount of liquid, that use all of the liquid to be implanted without waste, that can perform complete implants despite bubbles or kinks in the tube or catheter and that can successfully implant small, precise quantities of liquids by positive pressure rather than gravitational forces.